Static line parachutes are typically employed for relatively low altitude jumping applications, such as below 1500 feet above ground level. A typical static line parachute system incorporates a mechanism (the static line) for automatic deployment of the primary parachute, because of the relatively low altitude. Such a mechanism is used as a means of increasing parachute deployment reliability because the jumper would otherwise have a very short time to manually deploy the primary parachute at a safe altitude.
FIG. 1 illustrates a diagram of an exemplary static line parachute device 100. The static line parachute device 100 comprises a static line 102, a deployment bag 104, a breakable textile loop 105, a canopy 106, a plurality of suspension lines 107 and risers 108, a pack tray 110, and a harness 112. The static line 102 has a first end for attachment to the jumping platform, such as an airplane, helicopter, etc., and a second end attached to the deployment bag 104. The deployment bag 104 is, in turn, tied to the apex of the canopy 06 using a breakable textile loop 105. The canopy 106 is, in turn, attached to the harness 112 by way of the plurality of suspension lines 107 and risers 108. The harness 112 is attached to the pack tray 110, and is used to securely attach the jumper to the parachute device 100.
In the non-deployed state, the deployment bag 104 encloses the canopy 106 and externally stows the suspension lines 107 in an orderly fashion to aid parachute deployment, which lines connect to the risers 108, all of which are tightly packed within the pack tray 110. In addition, in the non-deployed state a portion of the static line 102 is also situated within the pack tray 110 but external to the deployment bag 104. When the jumper departs from the jumping platform, the portion of the static line 102 inside the pack tray 110 begins to unstow from the pack tray 110. After the unstowing of the static line 102 is complete, the tension force on the static line 102 caused by one end being fixed to the jumping platform and the other end attached to the falling deployment bag 104, pulls the deployment bag 104, canopy 106, suspension lines 107 and risers 108 out from the inside of the pack tray 110. As the jumper continues to fall and the deployment bag 104, canopy 106, suspension lines 107, and risers 108 are fully extended, the tension on the breakable textile loop 105 increases to a point at which the breakable textile loop 105 breaks due to its low strength characteristics. The canopy 106, now fully extended outside of the pack tray 110, encounters aerodynamic drag which forces the canopy to fully inflate to an open condition, which, in turn, normally slows the rate-of-descent of the jumper to a safe level.
In the majority of static line jumps, the parachute deploys in the intended way as described above. However, there are cases where the parachute deploys in an irregular manner, and which can sometimes lead to injuries and even lethal results for the jumper. Some of these cases relate to malfunctions concerning the static line. For instance, one such case is referred to in the relevant art as a “towed jumper” which occurs when a jumper becomes tangled in the static line. In addition, other lines, such as the ruck sack lowering line can also get caught on the jumping platform, leading to a “towed jumper” malfunction. Another case is when the static line breaks (“broken static line”), for example, by rubbing against a sharp edge portion of the jumping platform while a towed jumper oscillates up and down due to varying aerodynamic forces. Sometimes, the static line of a towed jumper breaks by impact from a subsequent jumper exiting the jumping platform.
Other cases relate to malfunctions with the canopy and/or the suspension lines. For instance, one case relates to a “damaged canopy” caused, for example, by tears or broken suspension lines, which damage results in an excessive rate-of-descent. Additionally, another case concerns a “suspension line entanglement” which limits the parachute from being able to fully inflate, resulting again in an excessive rate-of-descent. Furthermore, another case deals with a “line over entanglement” where some suspension lines deploy improperly over the top of the canopy, resulting in inadequate, or limited inflation of two or more smaller canopies having reduced drag causing again an excessive rate-of-descent.
Most, if not all, static line parachutes have a reserve parachute in case malfunctions occur with the deployment of the primary parachute. However, in these existing static line parachutes, the reserve parachute must be deployed manually by the jumper. A problem with such a manually-deployable reserve system is that the jumper may be incapable of deploying the reserve parachute if, for example, he collides with another jumper and becomes unconscious. Another problem concerns the desire for jumps at lower exit altitudes. At such lower altitudes, the jumper may not have sufficient time to recognize a problem has occurred with the primary parachute, and react to subsequently deploy the reserve parachute at a safe altitude.
Other types of automatic activation devices are available for free-fall parachutes. They function by releasing a reserve parachute at a preset altitude when a jumper's rate of descent exceeds a preset speed. Typically, these devices function based on an atmospheric pressure corresponding to the preset activation altitude and calculated in relation to the expected ground pressure where the jumpers will land. Dynamic pressure disturbances, which occur as a jumper exits the aircraft, can be as much as the equivalent of a 400-foot altitude change, depending on the aircraft speed, direction of the pressure sensor relative to the wind, and other parameters. Consequently, these types of free-fall automatic activation devices typically require a minimum altitude of 1,500 feet or more between the exit altitude and the ground to enable the device to function properly. Such requirements prevent using free-fall devices for static line parachute applications at low exit altitudes.
Thus, there is a need for a new system and method to improve the safety of static line parachute jumping. Such need and others are met with the static line parachute automatic actuation devices and related methods as described herein in accordance with the invention.